1. Field of the Invention
The present invention relates to an automatic document feeding device for feeding original documents to an exposure position and ejecting the original documents from said position in an image forming apparatus such as a copier.
2. Description of the Prior Art
In the known devices of this sort the transportation of the original document is stopped after the counting of clock pulses of a determined number from the detection of the leading end of the document. The stopping position of the original documents therefore fluctuate inevitably due to the incomplete precision in the thickness of a conveyor belt for transporting the original documents or in the dimension of a roller for driving said conveyor belt. Also such fluctuation results from the dimensional irregularity in the mounting mechanism of the copier for mounting the document feeding device. It has been extremely difficult to improve the dimensional precision in the mass production system.
Besides, such automatic document feeding device is generally so constructed that a copy start signal is automatically supplied to the copier for starting the copying operation when a transported original document is stopped on an original support face. Consequently the stopping position of the original document can only be confirmed by observing the copied image. Furthermore the testing of the function of the document feeding device inevitably causes the function of the copier itself, thus producing unnecessary copies.